Receiving ERR_CONNECTION_REFUSED intermittently while browsing websites

Question

I am unable to browse any website because on average, my connection would drop on every 4th HTTP request. This is also impacting my downloads and although they’d begin, they’d eventually fail before completion. I have tried browsing different websites on multiple browsers (chrome, firefox, safari) and over a Wi-fi connection and a wired ethernet line but received the same results. (Intermittent ERR_CONNECTION_REFUSED response)

After some research, I also tried disabling my firewall and looking for any proxies that I may have setup but that didn't help.

I tried debugging using curl and was able to consistently reproduce the issue. Executing “curl -l http://yahoo.com” from a terminal would return successfully but then after repeating it a few time it would return “curl: (52) Empty reply from server” and subsequently “curl: (7) Failed to connect to yahoo.com port 80: Connection refused”

Using Telnet, I noticed that although I would get connected, but then telnet would immediately exit with “Connection closed by foreign host” $ telnet www.yahoo.com 80 Trying 72.30.35.10... Connected to yahoo.com. Escape character is '^]'. Connection closed by foreign host.

Other laptops on the same network work without any issues. What could be going wrong?

Answer 1

I eventually found this post which prompted me to uninstall Cisco Anyconnect VPN Client on my MAC:

cd /opt/cisco/anyconnect/bin

sudo sh vpn_uninstall.sh

My problem was immediately resolved. Apparently, when installing Cisco AnyConnect VPN Client, you have to be careful not to install the Web Security module. (more information in this blog post I found linked in the Stack Overflow comment above) I’m not sure how this was an issue even though I didn’t have a VPN established, but its something I’ll try and look into more another day. Hope this helps someone else as well.